JP5266767B2 - Light control material, light control film, and method of manufacturing light control material - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a dimming material having excellent thermal resistance and dimming characteristics and a dimming film. <P>SOLUTION: In the dimming material containing a polymer medium which is hardened when it is irradiated with energy line and optical conditioning suspension distributed in the polymer medium, the optical conditioning suspension contains optical conditioning particles, nitrocellulose, and a dispersion medium separated from the polymer medium and its hardened material, and in an infrared absorption spectrum of mixture of the optical conditioning particles and nitrocellulose, the optical conditioning particles and nitrocellulose are contained at percentage that ratio of peak intensity of wavenumber 800-850 cm<SP>-1</SP>to peak intensity of wavenumber 780-800 cm<SP>-1</SP>becomes 0.2-0.6. <P>COPYRIGHT: (C)2009,JPO&amp;INPIT

Description

  The present invention relates to a light control material, a light control film, and a method for manufacturing the light control material.

  The light control film is a film in which the light transmittance changes depending on the magnitude of the applied electric field, and the amount of transmitted light can be adjusted. As a light control film, for example, a light control film using light adjusting particles having responsiveness to an electric field is known. In this light control film, fine droplets of a light control suspension in which light control particles are dispersed are dispersed in a resin matrix cured by ultraviolet irradiation. The resin matrix in which the light control suspension is dispersed is sandwiched between transparent conductive substrates as a light control layer. The light adjusting particles are preferably needle-shaped or rod-shaped. In this light control film, the light adjusting particles absorb, scatter, or reflect light by Brownian motion in a state where an electric field is not applied, so that incident light on the film cannot pass through the film. However, when the electric field is applied, the light adjusting particles are arranged in a direction parallel to the electric field due to the polarization of the light adjusting particles, so that the light incident on the film is transmitted through the film. Thus, in the light control film, the light transmission amount is adjusted by the response of the light adjusting particles to the electric field (see, for example, Patent Document 1).

  The light control particles used in the light control film are generally herpatite or polyhalide particles, but these fine particles have problems in heat resistance, water resistance, and repeated operation stability in the film, and are used commercially. It was not reached. Therefore, a technique for synthesizing a new precursor compound and improving the heat resistance of the light control particles has been proposed (see, for example, Patent Documents 2 to 4).

  On the other hand, nitrocellulose is indispensable for the synthesis of light control particles. However, nitrocellulose is known to affect the thermal stability of the light control film (see, for example, Patent Document 5), and from the viewpoint of thermal stability, it can be obtained by means such as centrifugation or dialysis. Nitrocellulose needs to be removed.

  However, since nitrocellulose plays the role of a protective colloid that prevents aggregation between the light control particles after synthesis, it is considered to be necessary for the expression of the light control characteristics. Therefore, the content of nitrocellulose coexisting with the light control particles is required to satisfy the requirements of both.

  Regarding the evaluation of nitrocellulose content, focusing on the fact that nitrocellulose has a characteristic infrared absorption, a method for evaluating the amount of nitrocellulose contained in explosives from the infrared absorption spectrum of explosives is already known. (For example, refer nonpatent literature 1).

JP-A-53-144893 Japanese Patent Laid-Open No. 5-17473 Japanese Patent No. 3448354 Japanese translation of PCT publication No. 2002-520646 JP-A-3-181918 Harada Munemasa, Mitsui Toshiyuki, Analytical Chemistry (Japan), 47, 1998, p. 867-871

  Then, an object of this invention is to provide the light control material and the light control film which were excellent in heat resistance and the light control characteristic in which content of nitrocellulose was adjusted in view of the above. Moreover, an object of this invention is to provide the manufacturing method for obtaining the light control material with the outstanding heat resistance and the light control characteristic with which content of nitrocellulose was prepared.

The inventors of the present invention have found that the content of nitrocellulose in a light-modulating material that has heretofore been difficult to evaluate can be evaluated by an infrared absorption spectrum, and have completed the present invention. It was.
The present invention is a light control material comprising a polymer medium that cures when irradiated with energy rays, and a light control suspension dispersed in the polymer medium, the light control suspension comprising: light control particles, nitrocellulose, and contains the polymeric medium and a cured product thereof and the phase separation to a dispersion medium, in an infrared absorption spectrum of the light control particles and nitrocellulose mixtures, to the peak intensity at a wavenumber 780～800Cm ^-1 The present invention relates to a light control material containing light adjusting particles and nitrocellulose at a ratio of a peak intensity of wave number 800 to 850 cm ⁻¹ being 0.2 to 0.6.
Moreover, this invention relates to the light control film formed using the said light control material.
Furthermore, the present invention is a method for producing a light control material comprising a polymer medium that is cured when irradiated with energy rays, and a light control suspension dispersed in the polymer medium, the light control material comprising: The suspension contains light adjusting particles, nitrocellulose, and a dispersion medium that is phase-separated from the polymer medium and a cured product thereof, and the content of nitrocellulose with respect to the content of the light adjusting particles by infrared absorption spectrum The present invention relates to a method for manufacturing a light-modulating material including a step of measuring the ratio.

  In the present invention, by defining the content of nitrocellulose with respect to the light control particles using an infrared absorption spectrum, it is possible to provide a light control material and a light control film having excellent thermal stability and light control characteristics. It has become possible. In addition, it is possible to easily manufacture a light-modulating material having excellent thermal stability and light-modulating characteristics by evaluating the content of nitrocellulose by infrared absorption spectrum in the process of manufacturing the light-modulating material. became.

The present invention will be described in detail below.
The light control material of this invention is a material used in order to obtain a light control film. The light control material of the present invention contains a polymer medium that cures when irradiated with energy rays, and a light-conditioning suspension dispersed in the polymer medium. The light adjustment suspension contains light adjustment particles, nitrocellulose, and a dispersion medium, and the dispersion medium is selected from a polymer medium and a material that is phase-separated from a cured product thereof. In the light control film of this invention, the light control layer which consists of a light control material hardened | cured with the energy ray is pinched | interposed by two board | substrates, such as a transparent conductive substrate. In the light control layer, a liquid light adjusting suspension is dispersed in the form of fine droplets in a solid resin matrix obtained by curing a polymer medium. As the light adjusting particles, needle-like or rod-like particles are preferable.

  Such a light control film absorbs, scatters, or reflects light due to Brownian motion of light control particles suspended and dispersed in a fluidized state in a droplet when no electric field is applied. The transmitted light can hardly pass through the film. However, when an electric field is applied to the light control film, since the light adjusting particles have an electric dipole moment, the light adjusting particles are arranged in a direction parallel to the electric field, so that light incident on the film is transmitted. Will come to let you. As described above, the light transmission amount can be adjusted by responding to the electric field to which the light adjusting particles are applied.

  In the present invention, the major axis of the light adjusting particles is preferably 200 to 500 nm, more preferably 250 to 450 nm, and further preferably 300 to 400 nm. Further, the minor axis of the light adjusting particles is preferably 30 to 90 nm, more preferably 40 to 70 nm, and further preferably 50 to 70 nm.

  The major axis and minor axis of the light adjusting particles in the present invention are obtained by photographing the light adjusting particles with an electron microscope such as a scanning electron microscope or a transmission electron microscope, and arbitrarily extracting 50 light adjusting particles from the photographed image, The major axis and minor axis of each light control particle can be calculated as an average value. Here, the long diameter is the length of the longest diameter of the light control particles projected in the two-dimensional visual field by the photographed image. Further, the minor axis is the length of the longest diameter orthogonal to the major axis.

The light adjusting particles in the present invention are preferably herpatite or polyhalide particles. Polyhalide particles include pyrazine-2,3-dicarboxylic acid dihydrate, pyrazine-2,5-dicarboxylic acid dihydrate, and pyridine-2,5-dicarboxylic acid monohydrate. Examples thereof include polyiodide prepared by reacting one substance selected from the above with iodine or iodide in an organic solvent. For example, calcium iodide can be used as the iodide. As polyhalide particles thus obtained, for example, the following general formula CaI ₂ (C ₆ H ₄ N ₂ O ₄ ) · XH ₂ O (X: 1 to 2)
CaI _a (C ₆ H ₄ N ₂ O ₄ ) _b · cH ₂ O (a: 3 to 7, b: 1 to 2, c: 1 to 3)
The thing represented by is mentioned. These polyhalide particles are preferably acicular crystals.

  Examples of the light control particles include US Pat. No. 2,041,138 (EH Land), US Pat. No. 2,306,108 (Land et al.), US Pat. The compounds disclosed in US Pat. No. 375,963 (Thomas), US Pat. No. 4,270,841 (RL Sax) and British Patent 433,455 can also be used. . The compounds disclosed therein are selected from polyazines such as polyiodide, polychloride or polybromide by selecting one of pyrazinecarboxylic acid or pyridinecarboxylic acid and reacting with iodine, chlorine or bromine. It is produced by. These polyhalides are complex compounds in which a halogen atom reacts with an inorganic substance or an organic substance, and their detailed production methods are disclosed, for example, in US Pat. No. 4,422,963 to Sax.

  Here, in the process of synthesizing the light control particles, nitrocellulose is used in the present invention in order to form particles of uniform size and to improve the dispersibility of the particles in the light control suspension. To do. By using nitrocellulose, when the light conditioning suspension is dispersed in the form of fine droplets in the solid resin matrix, the light conditioning particles are easily dispersed and floated in the fine droplets, There is a tendency for the response to an electric field to improve. Along with nitrocellulose, a polymer material for improving dispersibility such as polyacrylic acid can be used in combination.

  However, it is known that nitrocellulose is gradually decomposed at room temperature to generate nitrogen oxide, oxidized nitrogen dioxide and the like, and these oxides react with water to generate nitric acid and the like. Moreover, it is thought that acidic substances, such as nitric acid, degrade light control particle | grains, nitrocellulose, etc. by hydrolysis, and are estimated to be one of the big causes which reduce heat resistance etc. That is, nitrocellulose is indispensable for synthesizing the light control particles, preventing aggregation of the light control particles, and exhibiting the light control characteristics, but is also a causative substance of the light control film. Therefore, usually, after synthesis of the light control particles, more nitrocellulose than is necessary for the light control characteristics is separated and removed from the light control particles by means such as centrifugation.

  Generally, the light control particles are difficult to re-disperse in a dispersion medium such as an organic solvent or a polymer medium when the solvent is distilled off after the synthesis and dried to form a solid state. It is preferable to store in the state of a dispersion liquid dispersed in an organic solvent. The light adjusting suspension can be prepared using this dispersion.

  This dispersion is prepared by synthesizing the light control particles, removing coarse particles by centrifugation, further removing the supernatant, and then adding an organic solvent. This operation can be repeated until the unreacted product and nitroserose after synthesis are removed. However, in consideration of preparing the light-adjusting suspension using the dispersion, it is preferable to adjust the remaining amount of nitrocellulose in the dispersion to an appropriate amount at the stage of preparing this dispersion. .

  As a method for evaluating the amount of nitrocellulose, in the present invention, a method of observing an infrared absorption spectrum of a mixture containing light adjusting particles and nitrocellulose is used. The infrared absorption spectrum can be observed with respect to the mixture containing the light control particles and nitrocellulose at the same ratio as that of the light control particles and nitrocellulose contained in the light control suspension. Therefore, for example, in addition to the light adjustment suspension, it is also possible to carry out the dispersion liquid used for the preparation of the light adjustment suspension and the light control material including the light adjustment suspension. However, in consideration of the influence of peaks caused by other components contained in the light control material or the light control suspension, it is preferable to perform the evaluation at the stage of the dispersion. A specific method for evaluating the amount of nitrocellulose in the dispersion includes a method of observing an infrared absorption spectrum of a solid obtained by evaporating the organic solvent in the dispersion.

In general, when compounds 1 and 2 are present in the same thin film sample, and peaks attributed to each other are observed without overlapping (FIG. 1 (a)), the Beer-Lambert law (Equation 1) is Each peak holds (Equation 2). In FIG. 1A, A ₁ represents the peak intensity of Compound 1, and A ₂ represents the peak intensity of Compound 2. The ratio of absorbance (peak intensity) between A ₁ and A ₂ is proportional to the weight ratio of Compound 1 and Compound 2 as shown in Formula 3.

Also, when the peak of compound 1 partially overlaps the peak of compound 2 (FIG. 1 (b)), the ratio of absorbance (peak intensity) of A ₁ and A ₂ is still It is proportional to the weight ratio of the compound. In FIG. 1B, A ₀ is the peak intensity attributed to compound 2, A ′ ₁ is the peak intensity attributed to compound 1, A ₁ is the peak intensity attributed to compound 1 and compound 2, and A ₂ is the compound The peak intensity resulting from 2 is shown.

However, as shown in Formula 4, since the size of both intrinsic peaks cannot be determined strictly and the ratio of A ′ ₁ and A ₀ cannot often be specified, the accurate relationship between Compound 1 and Compound 2 It is difficult to determine the weight ratio. However, it is possible to evaluate the amount of Compound 1 relative to Compound 2 relative to the ratio of the peak intensities of A ₁ and A ₂ . Therefore, in the present invention, paying attention to a specific peak, the ratio of 1 to compound 2 is calculated.

This approach can be adapted to the light control particles and nitrocellulose, in which the peak appearing in the wavenumber 800～850Cm ^-1 as a peak attributable to nitrocellulose, due to peak appearing at a wave number of 780～800Cm ^-1 to the light control particles It is preferable to pay attention as a peak. In this case, although there is a peak due to the light adjusting particles at a wave number of 800 to 850 cm ⁻¹ , as described with reference to FIG. 1B, relative evaluation is possible even when the peaks overlap. .

Light control suspension in the present invention, the light control particles and nitrocellulose, the ratio of the peak intensity appearing at a wave number of 800～850Cm ^-1 to the peak intensity appearing at a wave number of 780～800Cm ^-1 is 0.2 to 0.6 , Preferably it contains in the ratio used as 0.2-0.5.

Specifically, the ratio between the light control particles and the nitrocellulose is the absorption at a wave number of 780 to 800 cm ⁻¹ when the infrared absorption of the solid obtained by drying the dispersion is observed and the vertical axis is the absorbance. It is preferable that the ratio of the peak height of the light and the peak height of absorption at a wave number of 800 to 850 cm ⁻¹ is in the range of 1: 0.2 to 1: 0.6. Furthermore, in order to improve heat resistance, it is preferable to exist in the range of 1: 0.2-1: 0.5.

The method for obtaining the solid to be measured is preferably a method in which a dispersion is applied on a KRS-5 or Si wafer, left to stand, and naturally dried. Moreover, in order to improve the measurement accuracy, the absorbance observed at 780 to 800 cm ⁻¹ and 800 to 850 cm ⁻¹ is preferably measured under conditions that are within the range of 0.1 to 1.0. .

  In order to make the ratio of the light adjusting particles and the nitrocellulose within the above range, a method of synthesizing the light adjusting particles and then removing the light adjusting particles or the nitrocellulose from the dispersion by, for example, centrifugation. Or the method of adding light control particle | grains or nitrocellulose to a dispersion liquid is mentioned.

  Next, in the present invention, the polymer medium that is cured by irradiation with energy rays includes, for example, a polymer compound that is cured by energy rays such as ultraviolet rays, visible rays, and electron beams, and a photopolymerization initiator. A molecular composition is mentioned. Examples of the polymer composition include a polymer composition containing a polymer compound having a substituent having an ethylenically unsaturated bond and a photopolymerization initiator.

  As the polymer compound having a substituent having an ethylenically unsaturated bond, a silicone resin, an acrylic resin, a polyester resin, and the like are preferable from the viewpoints of ease of synthesis, light control performance, durability, and the like. These resins are substituted with alkyl groups such as methyl group, ethyl group, propyl group, isopropyl group, butyl group, isobutyl group, tert-butyl group, amyl group, isoamyl group, hexyl group, and cyclohexyl group, and phenyl group. It is preferable to have an aryl group such as a naphthyl group from the viewpoints of light control performance and durability.

  Specific examples of the silicone resin include polymer compounds described in, for example, JP-B-53-36515, JP-B-57-52371, JP-B-58-53656, JP-B-61-17863, and the like. Can be mentioned.

  In addition, the silicone-based resin includes, for example, both-end silanol polydimethylsiloxane, both-end silanol polydiphenylsiloxane-dimethylsiloxane copolymer, both-end silanol siloxane polymers such as both-end silanol polydimethyldiphenylsiloxane, and trialkyl such as trimethylethoxysilane. Dehydrogenation condensation reaction and dealcoholization reaction of silane compounds containing ethylenically unsaturated bonds such as alkoxysilane and (3-acryloxypropyl) methyldimethoxysilane in the presence of 2-ethylhexanetin, which is an organotin catalyst. To be synthesized. The form of the resin is preferably a solventless type. That is, when a solvent is used for resin synthesis, it is preferable to remove the solvent after the synthesis reaction. The amount of the ethylenically unsaturated bond-containing silane compound such as (3-acryloxypropyl) methoxysilane is preferably 2 to 30% by weight, and preferably 5 to 18% by weight of the total amount of the raw material siloxane and silane compound. Is more preferable.

The acrylic resin includes, for example, (meth) acrylic acid alkyl ester, (meth) acrylic acid aryl ester, (meth) acrylic acid benzyl, main chain forming monomers such as styrene, (meth) acrylic acid, (meth) acrylic A prepolymer was synthesized by copolymerizing ethylenically unsaturated bond-introducing functional group-containing monomers such as hydroxyethyl acid, isocyanatoethyl (meth) acrylate, and glycidyl (meth) acrylate. By reacting monomers such as glycidyl (meth) acrylate, isocyanatoethyl (meth) acrylate, hydroxyethyl (meth) acrylate, (meth) acrylic acid, etc. to the prepolymer to react with the functional group of the polymer Can be obtained.
Moreover, the said polyester resin can be easily manufactured by a well-known method.

  The polystyrene equivalent weight average molecular weight obtained by gel permeation chromatography of the polymer compound having a substituent having an ethylenically unsaturated bond is preferably 20,000 to 100,000, and preferably 30,000 to 80. Is more preferable.

  When using the polymer compound having a substituent having an ethylenically unsaturated bond, a photopolymerization initiator that activates radical polymerization when exposed to energy rays can be used. Specifically, 2,2-dimethoxy-1,2-diphenylethane-1-one, 1- (4- (2-hydroxyethoxy) phenyl) -2-hydroxy-2-methyl-1-propan-1-one Bis (2,4,6-trimethylbenzoyl) phenylphosphine oxide, 2-hydroxy-2-methyl-1-phenylpropan-1-one, (1-hydroxycyclohexyl) phenyl ketone, and the like can be used.

The amount of these photopolymerization initiators used is preferably 0.05 to 20 parts by weight with respect to 100 parts by weight of the polymer compound having a substituent having an ethylenically unsaturated bond, More preferred are parts by weight. In addition to the polymer compound having a substituent having an ethylenically unsaturated bond, an organic solvent-soluble resin or thermoplastic resin having no substituent having an ethylenically unsaturated bond, for example, gel permeation Polyacrylic acid, polymethacrylic acid, and the like having a polystyrene-reduced weight average molecular weight of 1,000 to 100,000 measured by chromatography can be used in combination.
Moreover, you may add additives, such as coloring inhibitors, such as dibutyltin dilaurate, in a polymer medium as needed. Furthermore, the polymer medium may contain a solvent as necessary.

  In the present invention, as the dispersion medium in the light-adjusting suspension, one that is phase-separated from the polymer medium and a resin matrix that is a cured product thereof is used. Preferably, the light adjusting particles serve to disperse the light adjusting particles in a flowable state, and are selectively attached and coated on the light adjusting particles so that the light adjusting particles are phase-separated during phase separation from the polymer medium. Liquid that acts to move to the droplet phase, has no electrical conductivity, has no affinity with the polymer medium, and has a refractive index approximate to that of the resin matrix formed from the polymer medium when used as a light control film A copolymer is used. For example, a (meth) acrylic acid ester oligomer having a fluoro group and / or a hydroxyl group is preferred, and a (meth) acrylic acid ester oligomer having a fluoro group and a hydroxyl group is more preferred. When such a copolymer is used, one monomer unit of either a fluoro group or a hydroxyl group is directed to the light control particles, and the remaining monomer units are stably maintained as droplets of the light control suspension in the polymer medium. Therefore, the light adjusting particles are easily dispersed in the light adjusting suspension, and the light adjusting particles are easily induced in the phase-separated liquid droplet during the phase separation. Examples of the (meth) acrylic acid ester oligomer having such a fluoro group and / or hydroxyl group include 2,2,2-trifluoroethyl methacrylate / butyl acrylate / 2-hydroxyethyl acrylate copolymer, acrylic acid 3 , 5,5-trimethylhexyl / 2-hydroxypropyl acrylate / fumaric acid copolymer, butyl acrylate / 2-hydroxyethyl acrylate copolymer, 2,2,3,3-tetrafluoropropyl acrylate / acrylic Butyl acrylate / acrylic acid 2-hydroxyethyl copolymer, acrylic acid 1H, 1H, 5H-octafluoropentyl / butyl acrylate / acrylic acid 2-hydroxyethyl copolymer, acrylic acid 1H, 1H, 2H, 2H-hepta Decafluorodecyl / butyl acrylate / 2-hydroxy acrylate Chill copolymer, 2,2,2-trifluoroethyl methacrylate / butyl acrylate / 2-hydroxyethyl acrylate copolymer, 2,2,3,3-tetrafluoropropyl methacrylate / butyl acrylate / acrylic Acid 2-hydroxyethyl copolymer, methacrylic acid 1H, 1H, 5H-octafluoropentyl / butyl acrylate / acrylic acid 2-hydroxyethyl copolymer, methacrylic acid 1H, 1H, 2H, 2H-heptadecafluorodecyl / Examples thereof include butyl acrylate / acrylic acid 2-hydroxyethyl copolymer. Moreover, it is more preferable that these (meth) acrylic acid ester oligomers have both a fluoro group and a hydroxyl group.

  These (meth) acrylic acid ester oligomers preferably have a weight average molecular weight in terms of standard polystyrene measured by gel permeation chromatography of 1,000 to 20,000, preferably 2,000 to 10,000. Is more preferable. The amount of the fluoro group-containing monomer used as a raw material for these (meth) acrylic acid ester oligomers is preferably 6 to 12 mol%, more preferably 7 to 8 mol%, based on the total amount of monomers as raw materials. . When the usage-amount of a fluoro group containing monomer exceeds 12 mol%, there exists a tendency for a refractive index to become large and for the light transmittance to fall. Moreover, it is preferable that the usage-amount of the hydroxyl-containing monomer used as the raw material of these (meth) acrylic acid ester oligomers is 0.5-22.0 mol%, and it is more preferable that it is 1-8 mol%. When the usage-amount of a hydroxyl-containing monomer exceeds 22.0 mol%, a refractive index will become large and there exists a tendency for light transmittance to fall.

  The light control suspension in the present invention preferably contains 1 to 70% by weight of light control particles, more preferably 4 to 50% by weight, based on the total weight of the light control suspension. Moreover, it is preferable to contain 30 to 99 weight% of dispersion media with respect to the total weight of light adjustment suspension, and it is more preferable to contain 50 to 96 weight%.

  Moreover, it is preferable that a light control material contains 1-100 weight part of light adjustment suspension with respect to 100 weight part of polymer media, It is more preferable to contain 4-70 weight part, 6-60 More preferably, it is contained in an amount of 8 to 50 parts by weight.

  Next, the manufacturing method of the light control material of this invention is demonstrated. The method for producing a light-modulating material of the present invention is a method for producing a light-modulating material comprising a polymer medium that cures when irradiated with energy rays, and a light-conditioning suspension dispersed in the polymer medium. The light adjusting suspension contains light adjusting particles, nitrocellulose, and a dispersion medium that is phase-separated from the polymer medium and a cured product thereof, and the content of the light adjusting particles is determined by an infrared absorption spectrum. A step of measuring a ratio of the content of nitrocellulose. As described above, the measurement using the infrared absorption spectrum can be performed on the dispersion liquid, the light adjustment suspension, the light control material, and the like used for preparing the light adjustment suspension. The details of the measurement method are as described above. According to the production method of the present invention, the content of nitrocellulose with respect to the content of light adjusting particles can be adjusted to an arbitrary ratio.

  Next, the light control film of this invention has the light control layer containing the resin matrix formed from the polymer medium, and the light control suspension disperse | distributed in the resin matrix. Moreover, the light control film of this invention is formed by the said light control layer being preferably clamped between two transparent conductive substrates.

  The light control film of the present invention is formed by, for example, applying the light control material of the present invention on a transparent conductive substrate, irradiating energy rays to cure the polymer medium, and forming a light control layer. It can be manufactured by bringing a transparent conductive substrate into close contact therewith.

  Specifically, first, the light control suspension and the polymer medium are mixed to obtain a mixed liquid (light control material) in which the light control suspension is dispersed in a droplet state in the polymer medium. This mixed solution is applied on a transparent conductive substrate with a certain thickness, and after removing the solvent by drying as necessary, the polymer medium is cured by irradiating energy rays using a metal halide lamp, high-pressure mercury lamp, etc. Let As a result, a film is obtained in which the liquid light control suspension is dispersed in the form of droplets in the cured resin matrix containing the polymer medium. At this time, the light transmittance of the film can be adjusted by variously changing the mixing ratio of the polymer medium and the light control suspension. A light control film is obtained by bringing another transparent conductive substrate into close contact with the light control layer thus formed. Another transparent conductive substrate may be brought into close contact with the light control layer before irradiation with the energy beam, or may be brought into close contact with the light control layer during irradiation with the energy beam. Alternatively, a light control layer may be formed on both of the two transparent conductive substrates, and the light control layers may be laminated so that the light control layers are in close contact with each other. The thickness of the light control layer is preferably 5 to 1,000 μm, and more preferably 20 to 100 μm.

  As a method of obtaining a light control material in which the light control suspension is dispersed in a polymer medium in a droplet state, for example, the light control suspension and the polymer medium are mixed with a homogenizer, an ultrasonic homogenizer, etc. A method of finely dispersing the prepared suspension, a phase separation method by polymerization of polymer compound components in the polymer medium, a phase separation method by solvent volatilization when the polymer medium contains a solvent, a phase separation method by temperature, etc. Can be used.

  In addition, as a method for applying the light-modulating material on the transparent conductive substrate with a constant thickness, it is possible to use a coating means such as a bar coater, an applicator, a doctor blade, a roll coater, a die coater, and a comma coater, It can be applied to a substrate such as a conductive substrate. In addition, when apply | coating, you may dilute with a suitable solvent as needed. When a solvent is used, drying is required after coating on the substrate. As the solvent, for example, tetrahydrofuran, toluene, heptane, cyclohexane, ethyl acetate, ethanol, methanol, isoamyl acetate, hexyl acetate and the like can be used.

As the transparent conductive substrate, for example, a transparent substrate coated with a transparent conductive film such as ITO, SnO ₂ or In ₂ O ₃ can be used. The light transmittance of the transparent conductive film is preferably 80% or more, and the thickness of the transparent conductive film is preferably 10 to 5,000 nm. The light transmittance can be measured according to the total light transmittance measuring method of JIS K7105. Moreover, as a transparent substrate, glass, a polymer film, etc. can be used, for example.

  The above glass means a substrate transparent to visible light, etc., in addition to general glass mainly composed of silicon dioxide, glass of inorganic materials of various compositions, organic materials such as transparent acrylic resin, polycarbonate resin, etc. Resin glass using can also be used.

  Examples of the polymer film include polyester films such as polyethylene terephthalate, polyolefin films such as polypropylene, polyvinyl chloride, acrylic resin films, polyether sulfone films, polyarylate films, and polycarbonate films. However, a polyethylene terephthalate film is preferable because it is excellent in transparency and excellent in moldability, adhesiveness, workability, and the like. Although there is no restriction | limiting in particular in the thickness of a transparent substrate, For example, 1-15 mm is preferable in the case of glass, and 10-200 micrometers is preferable in the case of a polymer film.

  The surface resistance value of the transparent conductive substrate is preferably 3 to 600Ω. Moreover, when producing a light control film by narrowing the interval between transparent conductive substrates, in order to prevent a short-circuit phenomenon that occurs due to the mixing of foreign substances, 200-1,000 mm of the conductive film is formed on the transparent conductive film. You may use the board | substrate with which the transparent insulating layer of thickness is formed. When a reflective light control window such as a rear view mirror for automobiles is produced, a thin film of a conductive metal such as aluminum, gold, or silver that is a reflector may be directly used as an electrode.

  According to said method, the light control film which can adjust light transmittance arbitrarily by formation of an electric field is producible.

  In the light control film, the droplet size (average droplet diameter) of the light control suspension dispersed in the resin matrix is 0.5 to from the viewpoint of preventing aggregation and deposition of the light control particles. It is preferable that it is 50 micrometers, and it is more preferable that it is 1-10 micrometers. For the average droplet diameter, for example, using an optical microscope, take an image such as a photograph from one side of the light control film, and measure multiple droplet diameters (the longest droplet diameter) selected arbitrarily. The average value can be calculated. Further, it is also possible to take a visual field image of the light control film with an optical microscope into a computer as digital data and calculate it using image processing integration software. The size of the droplets depends on the concentration of each component constituting the light control suspension, the viscosity of the light control suspension and the polymer medium, and the compatibility of the dispersion medium in the light control suspension with the polymer medium. It is decided by etc.

  In addition, the refractive index of the liquid light-adjusting suspension and the refractive index of the polymer medium that cures when irradiated with energy rays are close to each other. It is preferable in terms of improvement.

  The conditions for exerting the light control performance are not particularly limited, but the power source used is normally AC, and can be operated in the frequency range of 10 to 220 volts (effective value) and 30 Hz to 500 kHz.

  The light control film of the present invention includes, for example, indoor and outdoor partitions, window glass / skylights for buildings, various flat display elements used in the electronics industry and video equipment, various instrument panels, and existing liquid crystal display elements. Suitable for applications such as light shutters, various indoor / outdoor advertisements and signboards, window glass for aircraft / railway vehicles / ships, window glass / back mirror / sunroof for automobiles, glasses, sunglasses, sun visors, etc. Can be used.

  As an application method, it is possible to directly use the light control film of the present invention. However, depending on the application, for example, the light control film of the present invention may be sandwiched between two base materials or used. It may be used by pasting it on one side. As said base material, glass, a polymer film, etc. can be used similarly to the said transparent substrate, for example.

  The structure and operation of the light control film of the present invention will be described in more detail with reference to the drawings.

  FIG. 2 is a structural schematic diagram of a light control film of one embodiment of the present invention, in which the light control layer 1 is between a transparent conductive substrate 4 composed of two transparent substrates 6 coated with a transparent conductive film 5. It is sandwiched. By switching the switch 8, the power supply 7 and the two transparent conductive films 5 are connected or disconnected. The light control layer 1 includes a film-shaped resin matrix 2 in which a polymer medium that is cured by irradiation with energy rays is cured, and a liquid light adjustment suspension dispersed in the form of droplets 3 in the resin matrix 2. Consists of a turbid liquid.

  FIG. 3 is a view for explaining the operation of the light control film shown in FIG. 2, and shows a case where the switch 8 is turned off and no electric field is applied. In this case, incident light 11 is absorbed by the light adjusting particles 10 due to Brownian motion of the light adjusting particles 10 dispersed in the dispersion medium 9 constituting the droplets 3 of the liquid light adjusting suspension. It is scattered or reflected and cannot be transmitted. However, as shown in FIG. 4, when an electric field is applied by connecting the switch 8, the light adjusting particles 10 are arranged in parallel with the electric field formed by the applied electric field. 10 passes. In this way, a light transmission function without scattering and a decrease in transparency is provided.

  EXAMPLES Hereinafter, although this invention is demonstrated further in detail based on an Example, this invention is not restrict | limited to the following Example.

(Production example of light control particles)
In order to produce the light control particles, a 500 ml four-necked flask equipped with a stirrer and a condenser tube was charged with 15% by weight of isoamyl acetate nitrocellulose 1 / 4LIG (trade name, manufactured by Bergerac NC, molecular weight 250,000) ( Reagent special grade, manufactured by Wako Pure Chemical Industries, Ltd.) 87.54 g diluted solution, 44.96 g isoamyl acetate, dehydrated CaI ₂ (water content 0.3%) (chemical, manufactured by Wako Pure Chemical Industries, Ltd.) 5 g, 2.0 g of anhydrous methanol (for organic synthesis, manufactured by Wako Pure Chemical Industries, Ltd.) and 0.45 g of purified water (purified water, manufactured by Wako Pure Chemical Industries, Ltd.) were added to iodine (JIS). Pyrazine-2,5-dicarboxylic acid dihydrate (manufactured by Nikka Techno Service Co., Ltd.), which is a substrate-forming substance for light control particles, is dissolved in 4.5 g of reagent special grade, manufactured by Wako Pure Chemical Industries, Ltd. 3 g was added. After stirring at 45 ° C. for 3 hours to complete the reaction, the mixture was dispersed with an ultrasonic disperser for 2 hours.

  Next, in order to take out light control particles having a certain size from the reaction solution, the particles were separated using a centrifuge. The reaction solution was centrifuged at a speed of 750 G for 10 minutes to remove the precipitate, and further centrifuged at 7390 G for 2 hours to remove the suspended matter and collect the precipitate. 88 g of isoamyl acetate was added to 9 g of the precipitate and dispersed to obtain an isoamyl acetate dispersion of light control particles. 0.05 g of the dispersion was sampled for measuring the infrared absorption spectrum.

  In a plastic bottle, 5 ml of isopentyl acetate and an isoamyl acetate dispersion of light control particles (a dispersion obtained by dispersing 9 g of the above precipitate in 88 g of isoamyl acetate) were placed in an ultrasonic dispersion for 5 minutes. Thereafter, an aluminum piece of 5 × 10 mm was immersed in the liquid for 10 seconds while ultrasonic dispersion was performed, and the light control particles were coated on the aluminum piece, taken out, and air-dried. The surface of the aluminum piece coated with the light control particles was photographed with a scanning electron microscope, 50 light control particles were arbitrarily extracted from the photographed image, and the major axis and the minor axis of the light control particles were measured. The light control particles had a major axis of 410 nm and a minor axis of 70 nm.

(Example of UV curable silicone resin production)
In a four-necked flask equipped with a Dean-Stark trap, condenser, stirrer, and heating device, 11.75 g of both-end silanol polydimethylsiloxane (manufactured by Shin-Etsu Chemical Co., Ltd.), both-end silanol polydimethyldiphenylsiloxane (Shin-Etsu Chemical) Industrial Co., Ltd.) 31 g, (3-acryloxypropyl) methyldimethoxysilane (Shin-Etsu Chemical Co., Ltd.) 4 g, 2-ethylhexane tin (Wako Pure Chemical Industries, Ltd.) 0.6 g are charged, The reaction was conducted by refluxing in heptane at 100 ° C. for 3 hours.

  Next, 10.6 g of trimethylethoxysilane (manufactured by Shin-Etsu Chemical Co., Ltd.) was added, refluxed for 2 hours, dealcoholized, and heptane was removed under reduced pressure at 80 ° C. for 3 hours at 60 Pa using a rotary evaporator. Thus, an ultraviolet curable silicone resin having a weight average molecular weight of 40,000 and a refractive index of 1.468 (a silicone resin having a substituent having an ethylenically unsaturated bond) was obtained.

Example 1
(Production example of light control suspension)
25.00 g (non-volatile component 7.40%) of the light adjustment particle isoamyl acetate dispersion obtained in the above (Production Example of Light Adjustment Particles) was used as a dispersion medium for the light adjustment suspension. , Wako Pure Chemical Industries, Ltd.) / 2,2,2-trifluoroethyl methacrylate (for industrial use, manufactured by Kyoeisha Chemical Co., Ltd.) / 2-hydroxyethyl acrylate (Wako Grade 1, Wako Pure Chemical Industries) (Co., Ltd.) Copolymer (monomer molar ratio: 18 / 1.5 / 0.5, weight average molecular weight: 2,200, refractive index 1.468) was added to 32.42 g and mixed with a stirrer for 30 minutes. Next, using a rotary evaporator, the pressure was reduced at 80 ° C. under a vacuum of 60 Pa for 3 hours to remove isoamyl acetate, and a light-controlled suspension was produced.

  14.11 g of this light control suspension and 6.90 g of decyl trimellitic acid (made by Kao Corp., plasticizer) were mixed, and 14.95 g of the resulting mixture (production example of UV curable silicone resin) 25.00 g of the ultraviolet curable silicone resin obtained in the above) and 0.2 g of bis (2,4,6-trimethylbenzoyl) phenylphosphine oxide (manufactured by Ciba Specialty Chemicals Co., Ltd.) as a photopolymerization initiator. Then, the light-modulating material was manufactured by mechanically mixing for 1 minute.

(Comparative Example 1)
15.00 g of the dispersion of the light control particles obtained in the above is mixed with 6.00 g of a nitrocellulose 1 / 4LIG 4.73 wt% isopentyl acetate diluted solution, and 0.05 g is sampled for infrared absorption spectrum measurement. Then, butyl acrylate / methacrylic acid 2,2,2-trifluoroethyl / 2-hydroxyethyl acrylate copolymer (monomer molar ratio: 18 / 1.5 / 0. 5, weight average molecular weight: 2,200, refractive index 1.468) In addition to 24.42 g, the mixture was mixed with a stirrer for 30 minutes. Next, using a rotary evaporator, the pressure was reduced at 80 ° C. under a vacuum of 60 Pa for 3 hours to remove isoamyl acetate, and a light-controlled suspension was produced.

  The UV-curable silicone resin 25 obtained by mixing 14.12 g of this light-adjusting suspension and 6.90 g of decyl trimellitic acid, and obtaining 14.97 g of the obtained mixture (Example of production of UV-curable silicone resin) 0.000 g and 0.2 g of bis (2,4,6-trimethylbenzoyl) phenylphosphine oxide as a photopolymerization initiator were mixed and mechanically mixed for 1 minute to produce a light control material.

(Comparative Example 2)
10.30 g of the isoamyl acetate dispersion of the light control particles obtained above was mixed with 10.00 g of a nitrocellulose 1 / 4LIG 4.73% by weight isopentyl acetate diluted solution, and 0.05 g was sampled for infrared absorption spectrum measurement. Then, butyl acrylate / methacrylic acid 2,2,2-trifluoroethyl / 2-hydroxyethyl acrylate copolymer (monomer molar ratio: 18 / 1.5 / 0. 5, weight average molecular weight: 2,200, refractive index 1.468) In addition to 21.30 g, the mixture was mixed with a stirrer for 30 minutes. Next, using a rotary evaporator, the pressure was reduced at 80 ° C. under a vacuum of 60 Pa for 3 hours to remove isoamyl acetate, and a light-controlled suspension was produced.

  The UV-curable silicone resin 25 obtained by mixing 14.10 g of this light-adjusting suspension and 6.90 g of decyl trimellitic acid, and obtaining 15.03 g of the resulting mixture (Example of production of UV-curable silicone resin) 0.000 g and 0.2 g of bis (2,4,6-trimethylbenzoyl) phenylphosphine oxide as a photopolymerization initiator were mixed and mechanically mixed for 1 minute to produce a light control material.

(Film production method)
The light control material obtained in Example 1 and Comparative Examples 1 and 2 is coated with a transparent conductive film (thickness 300 mm) of ITO (indium tin oxide), and the surface electrical resistance value is 200 to 300 Ω / Sq. Pull out a polyethylene terephthalate film (trade name 300R, manufactured by Toyobo Co., Ltd., thickness 125 μm) from the roll, and use an automatic coating machine (manufactured by Testa Industry Co., Ltd.) so that the dry film thickness is 45 μm on the roll. It apply | coated with the baker type applicator (scale 14), and laminated the same polyethylene terephthalate film as the above on the application layer. Then, using a metal halide lamp with an illuminance of 160 W / cm ² , UV-A is irradiated with ultraviolet rays of 4,000 mJ / cm ² , and the light-adjusting suspension is dispersed and formed in ultraviolet cured silicone resin as spherical droplets. A light control film having a light control layer was produced.

(Initial light transmittance)
The light transmittance of the obtained light control film when an electric field was applied was measured. The electric field is applied when an AC voltage (effective value) of 100 V is applied at 400 Hz. In addition, the light transmittance of the light control film is obtained by using a spectroscopic color difference meter (SZ-Σ90, manufactured by Nippon Denshoku Industries Co., Ltd.) and measuring the Y value (%) measured with an A light source and a viewing angle of 2 degrees. It was set as the transmittance | permeability (Table 1).

(Heat resistance test)
The obtained film was put into a dryer set at 95 ° C. and 110 ° C. and allowed to stand for 2 hours, and the light transmittance was measured again to evaluate the heat resistance (Table 1).

(Infrared absorption spectrum measurement)
The sampled dispersion was dropped on a Si wafer and allowed to stand for 30 minutes to air dry. The Si wafer was set in an apparatus Perkin Elmer Spectrum One FT-IR Spectrometer, and an infrared absorption spectrum was measured (FIG. 5). Each peak was determined to have the highest absorbance, and the ratio was calculated (Table 1).

  In a general method for producing light control particles, after light control particles are synthesized using nitrocellulose, coarse particles and unreacted substances are removed by centrifugation, or light control particles are collected. Therefore, it has been difficult to evaluate the amount of nitrocellulose contained in the light control suspension. According to the method for producing a light control material of the present invention, the content of nitrocellulose in the light control suspension can be adjusted to an appropriate range, and the light control material obtained thereby has heat resistance and Excellent dimming characteristics.

It is an infrared absorption spectrum conceptual diagram. It is a sectional structure schematic diagram showing one mode of a light control film of the present invention. It is the schematic for demonstrating the action | operation when the electric field of the light control film of FIG. 2 is not applied. It is the schematic for demonstrating the action | operation when the electric field of the light control film of FIG. 2 is applied. It is an infrared absorption spectrum of the dispersion liquid used in the Example and the comparative example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Light control layer 2 Resin matrix 3 Droplet 4 Transparent conductive substrate 5 Conductive thin film (transparent conductive film)
6 Transparent substrate 7 Power supply 8 Switch 9 Dispersion medium 10 Light control particle 11 Incident light

Claims (3)

A method for producing a light-modulating material comprising a polymer medium that is cured when irradiated with energy rays, and a light-conditioning suspension dispersed in the polymer medium,
The light control suspension contains light control particles, nitrocellulose, and a dispersion medium that is phase-separated from the polymer medium and a cured product thereof,
Obtaining a dispersion containing the light control particles and the nitrocellulose;
Using the dispersion, and measuring the ratio of the content of nitrocellulose to the content of light control particles by infrared absorption spectrum ,
Mixing the dispersion and the dispersion medium to obtain a light control suspension; and
A method for producing a light control material, comprising the step of mixing the light control suspension and the polymer medium .   The manufacturing method of the light control material of Claim 1 which further includes the process of adjusting the ratio of content of nitrocellulose with respect to content of light control particle | grains.   The dispersion is an isoamyl acetate dispersion in which the light control particles and the nitrocellulose are dispersed in isoamyl acetate, and the isoamyl acetate dispersion is dropped on a Si wafer, naturally dried, and the natural on the Si wafer As a value when the infrared absorption spectrum of the dried isoamyl dispersion was measured, the wave number was 780 to 800 cm. ^-1 Wave number 800-850cm for peak intensity ^-1 The manufacturing method of the light control material of Claim 1 or 2 which contains light-control particle | grains and nitrocellulose in the ratio used as the ratio of the peak intensity of 0.2-0.6.

Images